2025 REU Results
UW–Madison Astrophysics REU Program Summer 2025
Caroline Wraneschetz (College of Saint Benedict and Saint John’s University)
Measuring the Gas Distribution in a Planet-Forming Giant
Mentor: Abby Waggoner
Protoplanetary disks are rotating disks of gas and dust around pre-main sequence (<1 Myr) stars where the planet formation process occurs. Using data from the ALMA Survey of Gas Evolution in PROtoplanetary disks (AGE-PRO) program, this project studies six molecules—H2CO, DCO+, DCN, N2H+, CO, and C^34S—around the V1094 Sco protoplanetary disk. V1094 Sco is a Class II protoplanetary disk with an extremely large radius (R(90,dust)=353 au) and it is being studied to better understand its gas distribution. To complete this task, Keplerian masks were made and used to generate line spectra and moment zero maps. H2CO, N2H+, ^13CO, and C^18O were found to have brighter emission lines compared to DCO+, DCN, and C^34S. This is consistent with expected results, as rarer isotopes have fainter emission lines. The line spectra I generated will be used in future project with the Dust And LInes (DALI) chemical disk model to estimate the disk temperature, mass, and ionization rates of V1094 Sco.
Julia Lee (Mississippi State University)
Design of Magnetic Field Probes and Optical Systems for Beam-Steering Laser Calibration
Mentor: Dan McCammon
Half of the baryons in the universe are thought to be in the form of diffuse hot gas, which emits thermal energy in the form of X-rays. We aim to study X-ray emissions from the Local Hot Bubble, a nearby area of diffuse hot gas, using a pixel array of Transition Edge Sensors (TESs) with a large field of view in sounding rocket investigations. TESs are sensitive to magnetic fields both from Earth and from our refrigerator system, making it useful to have compact, robust magnetic field sensors for 3 directions. For calibration of the TESs, many UV laser pulses deliver thermal energy equivalent to that of the X-rays we hope to study. To allow the laser pulses to reach each pixel of the array, a beam-steering electromechanical mirror is mounted with an optic fiber, lens and stationary mirror that ensure a focused point of light on each sensor. This set up can continue to be refined to maximize the light delivered to each sensor and to allow for simple alignment of components.
Niha Das (Union College)
A Hunt for Intermediate Mass Black Holes in Low Mass and Low Metallicity Galaxies in SDSS-IV/eBOSS
Mentor: Christy Tremonti
Intermediate-mass black holes—black holes that are in between the mass ranges of stellar mass black holes and supermassive black holes (10^2 – 10^5 solar masses) — are considered difficult to detect and could be the missing link in black hole evolution. Therefore, understanding the demographics of these intermediate mass black holes is an important step in understanding how supermassive black holes that reside in the center of galaxies were formed in the early universe. Here, we are analyzing the data from the Sloan Digital Sky Survey’s (SDSS) Extended Baryon Oscillation Spectroscopic Survey (eBOSS) to look at spectra of 1286 low mass, low metallicity galaxies at redshift z < 0.15. One signature of accreting IMBHs is powerful outflows, which could appear as broad emission lines in the H-alpha or [OIII] 5007 line. To determine if our galaxies had those specific broad emission lines, we fit a Gaussian curve to the broad and narrow emission components. We find 125 candidates with robust broad lines in either [OIII] 5007 or H-alpha. Further analysis indicates that the majority of the broad lines have luminosities consistent with individual supernovae emissions; however, there appear to be two candidates with extremely broad OIII components with no H-alpha emission that are excellent IMBH candidates, requiring additional follow-up.
Annika Agarwal (Stevens Institute of Techology)
Cosmic Ray Anisotropy
Mentor: Paolo Desiati
My focus area this summer was on Cosmic Ray Anisotropy Distribution and analyzing different variables and factors that affect it. I was working with the IceCube Neutrino Observatory during this summer under my mentors. My main focus was on Cosmic Ray counts and their relationship to relative intensity, confounded with the IceCube instrumentation. Under that umbrella, I have been studying how amplitude and phase interact with these cosmic rays at different energy levels and the statistical significance and accuracy of these factors.
Zora Lewis (Colby College)
MINKE: A Multi-Component Emission Line Catalog to Trace Shock Excitation in NGC 1068
Mentor: Ralf Kotulla
NGC 1068 (M77) is a nearby Seyfert 2 galaxy with a Compton-thick active galactic nucleus (AGN), recently identified by IceCube as a high-energy neutrino source despite lacking the expected gamma-ray signature. In addition, archival HST narrow-band imaging revealed previously unrecognized filamentary Hα structures, possibly linked to AGN photoionization or shock excitation. Focusing on these features, we used optical spectroscopy from the WIYN SparsePak IFU to model Hα, [N II], and [S II] emission lines, fitting both narrow and broad components using Gaussian and Lorentzian profiles. We constructed a catalog of line fluxes, velocity dispersions, and ionization-sensitive [S II]/Hα ratios across the galaxy. Our results show enhanced line widths and elevated [S II]/Hα ratios near the nucleus and along extended structures, consistent with shock excitation, potentially tracing an AGN-driven outflow cone distinct from disk rotation. Mapping the extent and properties of this ionized gas provides valuable insight for identifying the processes that might contribute to the neutrino emission in NGC 1068.
Jacob Crawford (University of North Carolina – Asheville)
Comparing LyC Luminosity Inferred from HII Region Emissions and Model Expectations
Mentor: Bob Benjamin & Ed Mierkewicz
OB stars release massive fluxes of photons that ionize the molecular hydrogen in the star forming regions that birthed them. We used Hα emission data from the Wisconsin Hα Mapper (WHAM) to calculate velocity centroids of each HII region. We integrated the fluxes of Lyman continuum photons being emitted from the HII regions within the bounds of 3 sigma of each region’s velocity centroid, then compared them to the fluxes predicted by models of each HII region’s O stars. In this presentation, we will discuss progress on the project’s results.
Samantha McLean (Northern Arizona University)
Searching parameter space for the largest Balmer Break
Mentor: Michael Maseda
RUBIES-UDS-15418—a high-redshift luminous LRD monikered The Cliff—boasts an impressive balmer break strength. Measured at 6.9, The Cliff’s break strength is twice that of any source observed in prior surveys. This extraordinary source spurs us to ask, could there exist a stellar population capable of reproducing this break strength? This project performs a comprehensive sampling of parameter space, including an exploration of unusual star formation histories (SFHs). Using prospector to generate models, we employ a Markov Chain Monte Carlo (MCMC) sampling using python’s emcee to commence a search for a set of parameters which can maximize the break. In our search, we find the tau parameter used to generate the SFH to be unconstrained by the MCMC sampling, and for the break strength to be maximized at log(Z☉)=0.5 and an age of 350 Myrs. For calculating the break strength, we find the indices used in De Graaff (2025) to be more sensitive to age and better at capturing the bluer end of the 4000 Angstrom break.